Belgium's Axel Witsel wins a header during the group H World Cup soccer match between Belgium and Algeria at the Mineirao Stadium in Belo Horizonte, Brazil, Tuesday, June 17, 2014. (AP Photo/Hassan Ammar)

BELO HORIZONTE, Brazil – Amid the never-ending permutations of tactics and formations that go into preparing for a World Cup elimination game, the United States has one critical task that can be simply defined.

If the Americans can find a way to disrupt the rhythm of Witsel, then their chances of springing an upset at Arena Fonte Nova will greatly increase.

"Witsel is strong. You can see that by looking at him," said Alexander "Sasha" Kerzhakov, his club teammate at Zenit St. Petersburg in the Russian Premier League. "But there are all the other things you might not expect. Fast with the feet, fast with the brain. Tackling, you don't get past him. And he can just go past you."

Belgium currently is enjoying a golden generation of young, talented players. The flashy skill comes from Chelsea's Eden Hazard, Manchester United's Adnan Januzaj, Napoli's Dries Mertens and others. The 6-foot-1 Witsel does the grunt work that makes their attacking possible but he also chips in his own graceful touches and clever tricks when he finds the time.

Consistent and composed but a deeply complex character, Witsel was mentally strong enough to cope with a pair of intense situations that threatened to disrupt his early career.

Back in 2009 in a game for Belgian club Standard Liege against Anderlecht, Witsel launched himself into an ill-timed tackle that shattered the lower leg of opponent Marcin Wasilewski, causing open fractures of the tibia and fibula. Witsel was banned for eight games, cast as a villain, lampooned by the Belgian media and so hated by Anderlecht fans that he received death threats. His parents had their home stoned by furious fans.

"It was the day that an elegant midfielder with the world at his feet … became a beast," Belgian journalist Kristof Terreur wrote in the Guardian.

The ruckus caused Witsel to move overseas, first to Benfica in Portugal and then to Russia with Zenit in a blockbuster move worth $55 million in transfer fees. Witsel's salary at Zenit, more than $4 million, caused so much friction among the players that Russian president Vladimir Putin even weighed in on the debate defending the club's right to sign high-priced foreigners.

To add to it all, Witsel was also the first black player signed by Zenit, a club with a notoriously racist subsection of fans and with little forgiveness for poor performance.

Witsel won them over. He directs traffic for Zenit, which has finished second in Russia's top league the past two seasons, just like he does for Belgium, which cruised through qualifying and has won all three group games in Brazil. U.S. midfielders Michael Bradley, Kyle Beckerman and Jermaine Jones will have their hands full.

Witsel doesn't say a whole lot, preferring to let his game and others do the talking. Belgian coach Marc Wilmots has described him as the heartbeat of the team. Following the Wasilewski injury, Witsel became smarter. He is still rough and tough, but his timing is better. He is just as ruthless but no longer reckless.

"Think for a minute about what it says about him that he has been given the keys to this team," said Christopher Sullivan, Yahoo Sports soccer analyst and former U.S. national team member. "That is such a talented squad and he is the guy they have got operating as the engine. That means one thing – he has outstanding quality."

But when Witsel comes knocking, the Americans cannot afford to be scared. Klinsmann's men will take a similar approach to when they played Portugal and were aware of Cristiano Ronaldo, without obsessing over him.

"Like I said before it is not only Cristiano for Portugal, they have a good group too," Jones said. "Belgium has not only Witsel. Every player who plays in this team plays in a big club team. So it is completely the whole team so we have to be focused on everybody."

But the U.S. will know what it is up against, even if it will play its cards close to its chest this week. Klinsmann has a deep respect for midfielders who can assert themselves physically but retain the technical ability and clarity of thought to set up decisive attacks.

Pre-game tactical analysis will be comprehensive, but you can bet that much time will be spent with Bradley, Beckerman and Jones on formulating a plan.